User talk:Phlox/Ontology notes
So SMW doesn't replace categories soon if ever but works with them? It may reduce the value of producing lots of high-level, complex cats, such as "Migrants from Europe to Canada in the 1820s"? — Robin Patterson (Talk) 12:06, 16 May 2009 (UTC) :Actually, it looks like they are categories with a bunch of extra features. :#You can query on categories and properties, except you can add numeric or date range checks if they are properties :#You assign the item to a property nearly like you do a category, except you use two colons instead of one. birth county::Gloucestershire :#When you create a property page, the items marked with that property appear as a list. :#*except: sub properties are not listed (fixed in SMW 1.2.1. release- this limitation will go away as soon) :#*except: lists are formatted differently - less compressed and with special features for examining the values. :#You can declare a default form for a category, just as you can for a property :#if you search for categories, it picks up articles from all subcats. The same is true of properties. For instance, search on property state picks up death state, birth state, wedding1 state and so on. :#creating sub properties is alike, but syntax is slightly different. With cat's you simply mention the supercat eg Category:Counties of Colorado. If counties of colorado were a property, the corresponding syntax would be subproperty of::Property:Counties of Colorado. :#Categories and properties can be used interchangably in queries. You can create a query eg one that combines Migrants from Europe with Migrants to Canada with Migration date before 1830 and after 1819. Migrants from Europe and Migrants to Canada could be either categories or properties. Migration date could not be a property, due to the range comparison. :So it is not so very odd after all. By the way, the combined query above can be saved as a "Concept". There is a bit of hyperbole in calling it a concept, but the idea is that it is a saved query so instead of typing in all that query again, you can simply type Concept:Migrants from Europe to Canada in the 1820s. You can use these in other queries, or on pages just as if it were a property. Concept:1750s births implements the category:1750s births. There may be performance reasons for using Categories rather than Concepts, but I have not yet determined this yet. They may cache the results on the server for all I know, but I notice a lag when I use concepts versus categories. :Hope this helps. Maybe we should collect these remarks somewhere useful. -[[User:Phlox|'~'' Phlox']] 18:15, 16 May 2009 (UTC) ::Thank you. Yes, we should collect them somewhere else. Not all of our users recognize that "Ontology" can be interesting. I'll give some thought to listing useful talk pages somewhere accessible and recognizable. One idea already formed is that we can make subpages of the SMW-site-derived Help page so that individual components can be expounded, locally illustrated, and discussed more easily. — Robin Patterson (Talk) 06:55, 17 May 2009 (UTC)